1. Field of the Invention
The present invention relates to a network control apparatus for controlling devices composing a communication network by, for example, setting routes and managing congestions and failures in the communication network, and relates to the communication network, which includes the apparatus.
2. Description of the Related Art
A communication network comprises a plurality of communication terminals, a plurality of relay apparatuses, transmission lines each connecting a relay apparatus to a communication terminal and transmission lines each connecting a relay apparatus to another relay apparatus. For example, the Internet, which becomes popular very fast, comprises personal computers (PCs) and workstations (WSxe2x80x2) each serving as a communication terminal, relay apparatuses such as routers and transmission lines such as optical fibers. Normally, in a communication between communication terminals, a route with a required bandwidth guaranteed between relay apparatuses connected to the communication terminals is set prior to the communication. It is also necessary to preserve a high communication quality by avoiding congestions and failures. In the conventional communication network, routes are set, and the communication quality is managed by a network management apparatus.
FIG. 43 is a diagram showing a typical configuration of the conventional communication network. As shown in FIG. 43, the conventional communication network comprises a plurality of communication terminals 2#1 and 2#2, a plurality of relay apparatuses 4#1 to 4#3 and a network control apparatus 6. The network control apparatus 6 gathers topology information showing a link state from each of devices on the communication network such as the relay apparatuses 4#i where i=1 to 3 and the communication terminals 2#i where i=1 to 2 by way of the Internet or dedicated lines. The network control apparatus 6 stores the topology information in a device-information database. The network control apparatus 6 receives a request for setting of routes from an external device such as a relay apparatus 4#i where i=1 to 3 or a communication terminal 2#i where i=1 to 2. For example, the network control apparatus 6 is requested to set routes at a bandwidth of 10 Mb/s between the communication apparatuses 2#1 and 2#2.
The network control apparatus 6 interprets information included in the request for setting of routes, and identifies devices on the routes being set to create device-setting information for the devices. When the network control apparatus 6 receives a request for setting of routes from a specific relay apparatus prior to communication of data destined for the communication terminal 2#2, for example, the network control apparatus 6 creates device-setting information indicating a relay apparatus to be used for relaying the communicated data and a bandwidth to be guaranteed, transmitting the information to the specific relay apparatus. The specific relay apparatus guarantees the specified bandwidth to be used between the specific relay apparatus and the relay apparatus specified in the device-setting information and transmits the communicated data to the relay apparatus specified in the information in accordance with the information. With the rapid growth of the communication network, however, the scale of the communication network becomes large and, if the number of relay apparatuses controlled by the network control apparatus rises, the following problems are raised.
1: The amount of communication network information stored in the device-information database increases substantially.
2: A load of processing to find an optimum route becomes large, because the number of relay apparatuses identified in a process of finding a route increases.
3: A load of connection management processing becomes large, because the number of relay-apparatus linked connections increases.
It is thus an object of the present invention addressing the problems described above to provide a network control apparatus that does not cause the amount of communication network information to rise even if the scale of the communication network becomes large.
It is another object of the present invention to provide a network control apparatus that does not cause a load of processing to find an optimum route to rise even if the scale of the communication network becomes large.
It is a further object of the present invention to provide a network control apparatus that does not cause the number of relay-apparatus linked connections to rise even if the scale of the communication network becomes large.
In accordance with an aspect of the present invention, there is provided a network control apparatus for controlling specific ones among a plurality of devices in a communication network divided into a plurality of areas wherein the specific devices are located in a predetermined one among the areas, the network control apparatus comprising: request-receiving means for receiving a first route-setting request requesting setting of a route between a device serving as a transmission destination and a device serving as a transmission source receiving communicated data from one of the devices; a database for storing device information identifying the controlled specific devices located in the predetermined area and topology information indicating a link of each of the specific devices to devices adjacent to the specific device; request-range-judging means for searching the database for a device serving as a transmission source and a device serving as a transmission destination specified in the first route-setting request and forming a judgment as to whether or not the first route-setting request is relevant to any of the controlled specific devices by determining whether the device serving as transmission source and the device serving as a transmission destination are among the controlled specific devices; request-transmitting means for transmitting the first route-setting request to an upper-level network control apparatus controlling the network control apparatus in the case of the request-range-judging means"" judgment outcome indicating that the first route-setting request is irrelevant to any of the controlled specific devices; route-finding means for finding a route between the device serving as a transmission destination and the device serving as a transmission source on the basis of the first route-setting request and the topology information in the case of the request-range-judging means"" judgment outcome indicating that the first route-setting request is relevant to any of the controlled specific devices; device-recognizing means for creating a device-setting request relevant to the route found by the request-range-judging means for each device on the route or for each lower-level network control apparatus controlling one of the areas passed through by the route; and request and information-transmitting means for transmitting the device-setting request to each device on the route or each lower-level network control apparatus controlling one of the areas passed through by the route.
In accordance with another aspect of the present invention, there is provided a communication network: comprising a plurality of communication terminals, a plurality of relay apparatuses and a plurality of network control apparatuses; and treating each of the communication terminals, the relay apparatuses and the network control apparatuses like a device, wherein the network control apparatuses form a multi-branch tree structure in which: each of the network control apparatuses at the lowest level of the multi-branch tree structure controls a plurality of the communication terminals and a plurality of the relay apparatuses located in a predetermined one of a plurality of first areas composing the communication network; and each of the other network control apparatuses controls a plurality of the communication terminals and a plurality of the relay apparatuses located in a second area comprising some of the first areas each controlled by one of the network control apparatuses at the lowest level.
In the communication network according to the other aspect of the present invention, each of the network control apparatuses comprises: request-receiving means for receiving a first route-setting request requesting setting of a route between a device serving as a transmission destination and a device serving as a transmission source receiving communicated data from one of the devices; a database for storing device information identifying the controlled specific devices located in the predetermined area and topology information indicating a link of each of the specific devices to devices adjacent to the specific device; request-range-judging means for searching the database for a device serving as a transmission source and a device serving as a transmission destination specified in the first route-setting request and forming a judgment as to whether or not the first route-setting request is relevant to any of the controlled specific devices by determining whether the device serving as transmission source and the device serving as a transmission destination are among the controlled specific devices; request-transmitting means for transmitting the first route-setting request to an upper-level network control apparatus controlling the network control apparatus in the case of the request-range-judging means"" judgment outcome indicating that the first route-setting request is irrelevant to any of the controlled specific devices; route-finding means for finding a route between the device serving as a transmission destination and the device serving as a transmission source on the basis of the first route-setting request and the topology information in the case of the request-range-judging means"" judgment outcome indicating that the first route-setting request is relevant to any of the controlled specific devices; device-recognizing means for creating a device-setting request relevant to the route found by the request-range-judging means for each device on the route or for each lower-level network control apparatus controlling one of the areas passed through by the route; and request and information-transmitting means for transmitting the device-setting request to each device on the route or each lower-level network control apparatus controlling one of the areas passed through by the route.
The above and other objects, features and advantages of the present invention as well as the manner of realizing them will become more apparent, whereas the invention itself will be best understood from a study of the following description and appended claims with reference to the attached drawings showing some preferred embodiments of the invention.